A border dispute between Malaysia and Singapore has resurfaced, with Prime Minister Mahathir Mohamad himself getting involved in the public spat this week. We praise Singapore’s Prime Minister Lee Hsien Loong for not responding openly to Mahathir’s claim, as the latter is simply singing the same old song. Exaggerating the long-standing problem would be counterproductive for both sides.

As a senior leader, Mahathir, who turned 93 in July, needs to change his confrontational and hostile approach toward Singapore and act as a mature statesman. The advice of one of the founding fathers of the United States, Benjamin Franklin, to not “throw stones at your neighbors’, if your own windows are glass” is apt.

The territorial conflict between the two neighbors resumed on Wednesday when Mahathir denied Singapore’s claim that the planned expansion of the Johor Baru Port vio...